CHARACTERIZATION OF MONOAMINE NEURAL ACTIVITY IN THE PREOPTIC-ANTERIOR HYPOTHALAMIC AREA AND MEDIAL BASAL HYPOTHALAMUS IN RATS DURING THE DAY OF PRO-ESTRUS AND ITS RELATION TO GONADOTROPIN AND SEXUAL STEROID-HORMONE PLASMA-LEVELS

We have investigated the dynamic changes in monoamine concentration an d monoaminergic neural activity in the preoptic-anterior hypothalamic area (POA-AHA) and medial basal hypothalamus (MBH) in rats during the day of pro-oestrus and their relationship with serum levels of luteini zing hormone, follicle stimulating hormones, oestradiol and progestero ne. In the POA-AHA there was no evident temporal relationship between monoaminergic neural activity and the LH pre-ovulatory surge. In the M BH NE and DA neural activity increased from 09.00 to 15.00, with high concentrations of 17 beta-oestradiol prior to the LH peak. The rise in NE and DA neuronal activity in the MBH prior to the LH serum level pe ak suggests that such monoamines could modulate gonadotrophin releasin g hormone release in a stimulatory way. (C) 1998 Lippincott-Raven Publ ishers.